There is a lead terminal which includes a structure in which a high electric conductivity material is used as a substrate and is sandwiched from the opposite side faces at a central portion thereof by low heat conductivity electric conductivity materials leaving coupling portions at the opposite ends thereof such that the high electric conductivity material and the low heat conductivity electric conductivity materials are overlapped with and pressure welded to each other.
Meanwhile, there is a surface mount type coil which includes a drum type core including a pair of flanges formed integrally at the opposite ends of a wrapping core, a winding wound on the wrapping core and base electrodes provided on a circumferential face and an end face of the flanges at the opposite ends of the drum type core and having end portions of the winding coupled thereto (refer to Patent Document 2). An exterior member covers over an area from part of the base electrode on the circumferential face of one of the flanges to part of the circumferential face of the other flange. Terminal electrodes cover over the base electrodes from above the exterior member on the flange circumferential faces. Missing portions expose the base electrodes at projections of the exterior member on the circumferential face of the flanges, which extend toward an end portion of the flanges and regions rather near to the winding core than the projections.
However, since the substrate of a high heat conductivity is left at part of a heat conduction path, thermal energy flows to the electronic part side, and sufficient thermal energy does not stay at the lead terminal and the lead terminal sometimes fails to have a temperature of the melting point of the solder. As a result, it is difficult to solder the lead terminal well.
The followings are reference documents.
[Document 1] Japanese Laid-open Utility Model Publication No. 63-16423, and
[Document 2] Japanese Laid-open Patent Publication No. 2001-155937.